Put the garlic and ginger in the bowl of a food processor and process until finely chopped.,Add the mayonnaise, sesame oil, lime juice, soy sauce, and vinegar and process until well blended.,Scrape the vinaigrette into a bowl and set aside until needed.,Makes about 1/2 cup.,In the same work bowl of the food processor, process the shallot until finely chopped.,Add the fish and pulse until roughly chopped.,Scrape the fish into a large bowl and add the cilantro, the 2 tablespoons of vinaigrette, and 1 1/2 teaspoons of pepper.,______,Using your hands, shape the fish into 4 evenly sized burgers about 1 inch thick.,Cover and refrigerate for at least 30 minutes or as long as several hours to allow the flavors to develop.,When ready to cook, heat 2 tablespoons of the olive oil in a large skillet or grill pan over medium-high heat until very hot or build a medium-hot fire in a barbecue.,Brush the burgers on both sides with olive oil and season well with salt and pepper.,Cook the burgers, turning once or twice, until golden brown on both sides, about 5 minutes.,Take care not to overcook them.,They should be rare to medium-rare.,To grill the burgers, oil the rack, and cook the burgers, covered, about 5 minutes, turning once.,As the burgers cook, toast the buns in a toaster oven or under the broiler, about 5 inches from the heat, until lightly toasted.,Or toast them on the outer perimeter of the grill rack.,To build the burgers, in a medium bowl, toss the spinach with half the reserved vinaigrette.,Divide the spinach among the bun bottoms.,Top with a burger and then spoon a little more vinaigrette on top.,Cover with the tops of the buns and serve immediately.